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1. Achievable Rate of a SISO System Under Wideband Matching Network Constraints

   https://doi.org/10.1109/GLOBECOM54140.2023.10437975  

   Deshpande, Nitish Vikas ; Castellanos, Miguel R. ; Khosravirad, Saeed R. ; Du, Jinfeng ; Viswanathan, Harish ; Heath, Robert W. ( December 2023 , IEEE)

   Conventional achievable rate analysis using Shan- non’s theory does not assume practical constraints imposed by Bode-Fano wideband matching theory. This leads to an achiev- able rate bound that cannot be attained by practical matching networks. In this paper, we generalize the information-theoretic achievable rate of a single-input-single-output (SISO) system by incorporating wideband matching constraints at the transmitter. We express the solution to the achievable rate optimization problem in terms of the optimized transmission coefficient and the Lagrangian parameters corresponding to the Bode-Fano inequality constraints. We also propose a practical strategy to design a physically realizable matching network through the ADS software which attains the achievable rate bound with near- optimality. In simulations, we apply this framework to a Chu’s antenna and compare the achievable rate performance with the conventional conjugate matching strategy. 

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2. Achievable Rate with Antenna Size Constraint: Shannon meets Chu and Bode

   https://doi.org/10.1109/TCOMM.2021.3099842  

   Shyianov, Volodymyr ; Akrout, Mohamed ; Bellili, Faouzi ; Mezghani, Amine ; Heath, Robert W. ( January 2021 , IEEE Transactions on Communications)

   null (Ed.)

   Using ideas from Chu and Bode/Fano theories, we characterize the maximum achievable rate over the single-input single-output wireless communication channels under a restriction on the antenna size at the receiver. By employing circuit-theoretic multiport models for radio communication systems, we derive the information-theoretic limits of compact antennas. We first describe an equivalent Chu’s antenna circuit under the physical realizability conditions of its reflection coefficient. Such a design allows us to subsequently compute the achievable rate for a given receive antenna size thereby providing a physical bound on the system performance that we compare to the standard size-unconstrained Shannon capacity. We also determine the effective signal-to-noise ratio (SNR) which strongly depends on the antenna size and experiences an apparent finite-size performance degradation where only a fraction of Shannon capacity can be achieved. We further determine the optimal signaling bandwidth which shows that impedance matching is essential in both narrowband and broadband scenarios. We also examine the achievable rate in presence of interference showing that the size constraint is immaterial in interference-limited scenarios. Finally, our numerical results of the derived achievable rate as function of the antenna size and the SNR reveal new insights for the physically consistent design of radio systems. 

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3. Beamforming optimization of wideband MISO systems in the presence of mutual coupling

   https://doi.org/10.1109/IEEECONF51394.2020.9443408  

   Saab, Sandy ; Mezghani, Amine ; Heath, Robert W. ( November 2020 , Proceedings of the Asilomar Conference on Signals, Systems and Computers)

   null (Ed.)

   We introduce a mutual information based optimization for a two-port multiple-input single-output (MISO) antenna system. We develop a complete circuit-level analysis of a compact MISO system in the wideband regime. We design a physically realizable antenna array and study the impact of mutual coupling on the spectral efficiency. Then, we maximize the system's mutual information by optimizing the beamformer under two different power constraints, namely the total dissipated power and the available power of the amplifiers. By varying the inter-element antenna spacing, we present results for the achievable spectral efficiency under different power amplifier constraints. 

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4. Simple Caching Schemes for Non-homogeneous MISO Cache-Aided Communication via Convexity

   https://doi.org/10.1109/ICASSP40776.2020.9053936  

   Bergel, Itsik ; Mohajer, Soheil ( May 2020 , ICASSP 2020 - 2020 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP))

   We present a novel scheme for cache-aided communication over multiple-input and single output (MISO) cellular networks. The presented scheme achieves the same number of degrees of freedom as known coded caching schemes, but, at much lower complexity. The scheme is derived for communication systems with heterogeneous rates and finite signal-to-noise ratio, in which links are modeled by wideband fading channels. The base station is serving multiple users simultaneously, by sending a combination of several packets, each intended for one user. The interference is either suppressed using the cache content or nulled by zero-forcing at the unintended users. We focus on efficient coding schemes, which allow for a maximum number of users to be served throughout the course of communication. An achievable rate region is characterized by determining the extreme rate vectors satisfying an efficient transmission. The analysis results in a simple scheduling scheme and in a closed-form performance analysis. 

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5. Achievable Rates for Low-Complexity Posterior Matching over the Binary Symmetric Channel

   https://doi.org/10.1109/TIT.2023.3322095  

   Antonini, Amaael ; Gimelshein, Rita ; Wesel, Richard ( October 2023 , IEEE Transactions on Information Theory)

   Horstein, Burnashev, Shayevitz and Feder, Naghshvar et al . and others have studied sequential transmission of a k-bit message over the binary symmetric channel (BSC) with full, noiseless feedback using posterior matching. Yang et al . provide an improved lower bound on the achievable rate using martingale analysis that relies on the small-enough difference (SED) partitioning introduced by Naghshvar et al . SED requires a relatively complex encoder and decoder. To reduce complexity, this paper replaces SED with relaxed constraints that admit the small enough absolute difference (SEAD) partitioning rule. The main analytical results show that achievable-rate bounds higher than those found by Yang et al . [2] are possible even under the new constraints, which are less restrictive than SED. The new analysis does not use martingale theory for the confirmation phase and applies a surrogate channel technique to tighten the results. An initial systematic transmission further increases the achievable rate bound. The simplified encoder associated with SEAD has a complexity below order O ( K 2 ) and allows simulations for message sizes of at least 1000 bits. For example, simulations achieve 99% of of the channel’s 0.50-bit capacity with an average block size of 200 bits for a target codeword error rate of 10 -3. 

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